Giant Magnetocaloric Effect in Magnets Down to the Monolayer Limit

2D magnets can potentially revolutionize information technology, but their potential application to cooling technology and magnetocaloric effect (MCE) in a material down to the monolayer limit remain unexplored. Herein, it is revealed through multiscale calculations the existence of giant MCE and its strain tunability in monolayer magnets such as CrX3 (X = F, Cl, Br, I), CrAX (A = O, S, Se; X = F, Cl, Br, I), and Fe3GeTe2. The maximum adiabatic temperature change (Delta T-ad(max)), maximum isothermal magnetic entropy change, and specific cooling power in monolayer CrF3 are found as high as 11 K, 35 mu J m(-2) K-1, and 3.5 nW cm(-2) under a magnetic field of 5 T, respectively. A 2% biaxial and 5% a-axis uniaxial compressive strain can remarkably increase Delta T-ad(max) of CrCl3 and CrOF by 230% and 37% (up to 15.3 and 6.0 K), respectively. It is found that large net magnetic moment per unit area favors improved MCE. These findings advocate the giant-MCE monolayer magnets, opening new opportunities for magnetic cooling at nanoscale.

Automated summary

The existence of giant magnetocaloric effect (MCE) and its strain tunability in monolayer magnets, including CrX3 (X = F, Cl, Br, I), CrAX (A = O, S, Se; X = F, Cl, Br, I), and Fe3GeTe2, has been revealed through multiscale calculations. The maximum values of adiabatic temperature change (Delta T-ad(max)), isothermal magnetic entropy change, and specific cooling power in monolayer CrF3 are found to be as high as 11 K, 35 mu J m(-2) K-1, and 3.5 nW cm(-2) under a magnetic field of 5 T, respectively. The application of compressive strain can significantly increase Delta T-ad(max) of CrCl3 and CrOF by 230% and 37% (up to 15.3 and 6.0 K), respectively. It is observed that a large net magnetic moment per unit area favors improved MCE. These findings provide new opportunities for magnetic cooling at the nanoscale.